1. Field of the Invention
Embodiments disclosed herein generally relate to buffer layers for thin film semiconductors. More specifically, embodiments disclosed herein generally relate to high work function and low electron affinity layers.
2. Description of the Related Art
Current interest in thin film transistors (TFTs) is particularly high because these devices may be used in liquid crystal active matrix displays (LCDs) of the kind often employed for computer and television flat panels. The LCDs may also contain light emitting diodes (LEDs), such as organic light emitting diodes (OLEDs) for back lighting. The LEDs and OLEDs require TFTs for addressing the activity of the displays. One of the applications for the semiconductor is for the thin-film transistor traditionally used for displays.
The current driven through the TFTs (i.e., the on-current) is limited by the channel material (often referred to as the active material, semiconductor material or semiconductor active material) as well as the channel width and length. Additionally, the turn-on voltage is determined by the accumulation of the carrier in the channel area of the semiconductor layer which could change as the shift of the fixed charge in the semiconductor material or the charge trapping in interfaces and the threshold voltage shifts after bias temperature stress or current temperature stress.
In current MO-TFTs, the interface between layers, such as the interface between the gate dielectric layer and the metal oxide semiconductor layer, can be problematic for the overall function of the device. In indium gallium zinc oxide (IGZO), zinc oxide (ZnO) and zinc oxynitride (ZnON) TFT devices, problems can include mobility problems and turn on voltages.
Therefore, there is a need in the art for methods and devices to reduce interface problems for TFT devices.